title: Immediate and delayed effects of mammographic screening on breast cancer mortality and incidence in birth cohorts.
abstract: BACKGROUND
  Trend studies investigating the impact of mammographic screening usually display age-specific mortality and incidence rates over time, resulting in an underestimate of the benefit of screening, that is, mortality reduction, and an overestimate of its major harmful effect, that is, overdiagnosis. This study proposes a more appropriate way of analysing trends.
  
  
  METHODS
  Breast cancer mortality (1950-2009) and incidence data (1975-2009) were obtained from Statistics Netherlands, 'Stg. Medische registratie' and the National Cancer Registry in the Netherlands for women aged 25-85 years. Data were visualised in age-birth cohort and age-period figures.
  
  
  RESULTS
  Birth cohorts invited to participate in the mammographic screening programme showed a deflection in the breast cancer mortality rates within the first 5 years after invitation. Thereafter, the mortality rate increased, although less rapidly than in uninvited birth cohorts. Furthermore, invited birth cohorts showed a sharp increase in invasive breast cancer incidence rate during the first 5 years of invitation, followed by a moderate increase during the following screening years and a decline after passing the upper age limit.
  
  
  CONCLUSIONS
  When applying a trend study to estimate the impact of mammographic screening, we recommend using a birth cohort approach.
authors.affiliation: Department for Health Evidence, Radboud University Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands.
authors.forename: T M
authors.initials: TM
authors.lastname: Ripping
authors.forename: A L M
authors.initials: AL
authors.lastname: Verbeek
authors.forename: D
authors.initials: D
authors.lastname: van der Waal
authors.forename: J D M
authors.initials: JD
authors.lastname: Otten
authors.forename: G J
authors.initials: GJ
authors.lastname: den Heeten
authors.forename: J
authors.initials: J
authors.lastname: Fracheboud
authors.forename: H J
authors.initials: HJ
authors.lastname: de Koning
authors.forename: M J M
authors.initials: MJ
authors.lastname: Broeders
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000453:epidemiology* / Q000401:mortality; D015331:Cohort Studies; D055088:Early Detection of Cancer / Q000379:methods; D005260:Female; D006801:Humans; D015994:Incidence; D008327:Mammography / Q000379:methods; D008403:Mass Screening / Q000379:methods; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology